Use more restrictive CSP in Chromium

[mymindstorm]

We may want to wait a while or save this for the MV3 transition due to the minimum version requirement.

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_Security_Policy#webassembly

[codecov[bot]]

Codecov Report

Merging #927 (ab4b90b) into dev (d34f98b) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #927   +/-   ##
=======================================
  Coverage   18.13%   18.13%           
=======================================
  Files          18       18           
  Lines        1544     1544           
  Branches      338      338           
=======================================
  Hits          280      280           
  Misses       1230     1230           
  Partials       34       34           

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